Brief:
Aerotech's take on the often modeled Navy Standard ARM is the "Strong ARM". It's not a particularly close scale rendition, but the result is good looking and well suited to F and G motors, particularly the EconoJets. There's a bit more to build in this kit than in the Aerotech Initiator or Mustang, but not so much that builders new to mid-power should be scared away. As mid-to-high power kits go it's still quite easy, especially if you work carefully and watch out for a few 'gotchas' that I will detail later.

Construction:
This is a single stage rocket with two body tubes joined with a coupler, 4 fins, and parachute recovery. This kit uses the same Fin-Lok system and baffle unit you find in all Aerotech kits. It's a medium sized rocket for Aerotech, 44 inches long and about pound and a half in weight when loaded for flight. The Aerotech catalog, btw, lists the weight of the rocket as 18 oz., but I don't know how they could get this weight. Something between 22oz to 25oz, seems more realistic.

This was the first kit I built from this manufacturer, though I have built other rockets of this size. I was eager to see how the famed Aerotech Fin-Lok system and baffle unit worked. I was also looking to get a new F and G motor bird in the fleet quickly and easily. I went to the Strong ARM thinking I'd have an relaxed time of it. As it turned out the construction was quite a bit more involved than I anticipated, but this does not have to be your experience, I just ran into some potholes along the way. In truth I have faced tougher challenges, and I did end up with a great rocket, but I was expecting something different.

The rocket arrives in a sturdy box that can become a display stand (nice!). The tubes are sturdy and pre-slotted, the fins are preformed. The engine mount parts are all there and seem well constructed. The engine clip is big and strong! The parachute is very nice, and the nosecone is...well, this was the first disappointment. The nosecone was a real mess. Easily the worst formed part I've ever experienced, from any manufacturer. I have seen other comments on Aerotech cones from others, but most folks are happy with theirs, so I think this is a quality control issue. If you get a good one, your doin' fine. If you get a bad one you have to decide how to handle it. I suspect that if you raise enough of a stink with Aerotech you can get a replacement. I didn't fully appreciate how much trouble this nosecone would give me when I first inspected it, so I elected to try to fix it (I did write Aerotech about it, though).

The generally excellent instructions have you start with the motor mount. This is where you will see the first signs of Aerotech's particular design philosophy. They design their kits to carry loads through the structure, and their rockets are therefore less reliant on heavy applications of glue (this from their documentation). I like this idea, but you will find that it has one downside; the rocket components must be built with very tight fits and close tolerances. The Aerotech corollary to the old saying "measure twice, cut once" is "test fit twice (or more), glue once". The best advice I can give you is, "don't touch that glue until you are absolutely sure how this part, and the parts that follow, will fit, and have verified that they do fit!" Read all the instructions before you start, and perhaps go to the Aerotech site and view the video of an Initiator construction, so you know what to expect.

Aerotech recommends that you build the rocket with medium CA, and I wanted to give that technique a try. I've never used CA in such large amounts on such large parts, and it takes some getting used to. You start off easy with the 24mm engine adapter, which is just a tube and two rings or sleeves. Aerotech provides a marking guide for the main motor tube, which is a nice touch. You need to be careful about keeping your "front edges" and "back edges" straight at this point. It can get confusing but it's important, so read the instructions very carefully and take it slow. The industrial size motor hook installs just like an Estes hook.

Now comes the first tricky part. The instructions tell you to put "several drops" of glue "just behind where the motor clip comes through the tube". Believe what they say. Use a small amount of glue and be sure to place it up next to the hook (also note that the motor block comes into the tube from the back or nozzle end, this is the reverse of the usual Estes procedure with engine hook equipped models). The engine block fits tight in the tube, and you need to get it all the way up to the hook before the CA glue 'grabs'. CA does not give you any chance to ease things into position once it starts to set. And it sets quick when the fit is tight and there's friction.

The next step is the initial fit of the Fin-Loks and centering rings. No glue at this stage, you need to test fits and positioning first. The fit is very tight, as mentioned above, but that's an important part of how the Fin-Lok system works. You check everything by snapping the fins into position in the Fin-Loks. It takes some force to get them in place, but you should feel and hear a definite "click" as it seats. This is a good time to get used to the 'feel' and force required. Once all the rings are properly placed and aligned, remove the fins (carefully, don't move the Fin-Lok rings!) and apply a very slight bead of CA to the Fin-Loks and front centering ring. The instructions are pretty insistent that you take great care to keep glue out of the Fin-Lok channels (where the fin will go). Again, believe what they tell you! CA is pretty low viscosity stuff, and it can flow around as you rotate the part. The clearances are very tight an even a small amount of glue will cause havoc.

Once the glue has set on the rings (pretty quick with CA), you get to build the baffle, which is fun. The "steel mesh" gets stretched out to six inches, then it slides into the tube, you cap the tube with a plastic baffle unit, add a third centering ring and screw an eye bolt into the baffle unit. The shock-cord ties to the screw eye. Easiest baffle I've ever built, and I like baffles. I have seen a Strong Arm (not mine thank goodness!) destroyed when the shock cord attachment separated at apogee. Either the cord broke, came untied or the screw pulled out, I did not hear the final verdict. In any case, this is the time to make sure you have a solid attachment.

Now it's time to place the motor and fin mount into the body and attach the fins. You slide the mount into the pre-slotted end of the body tube, but do not glue it yet. Aerotech would like you to glue the fins into place with CA "along the full length of the fin root" first. I'm going to suggest that you add a step. I did as I was told and, snapped one well glued fin into place. "Wow, that was easy!". Then I decided to attach the fin directly opposite the first, as I could push on the fin (and hence on the attached Fin-Lok rings) and not the body tube. Once you get a bead of CA down the length of your fin you tend to move quickly, the stuff sets fast! I slid the fin into place and pushed and..nothing! No "click". I pronounced a few expletives (that always helps) and gave it a harder push. Well, on the third push something happened, but it wasn't the Fin-Lok click I was looking for. The motor mount, remember, is not glued into place at this point. It's free to rotate in the tub! e, and that's what mine did under the considerable compression force I was exerting. That rotation caused the fin tabs on both fins to snap at their weak point (between the two Fin-Lok 'ridges' (It's tough to describe but obvious when you see it). Thankfully, this happened late at night when the kids were asleep, so they did not hear me "comment" on these events.

I was not aware, at that time, that you can buy these fins separately from Aerotech, and I was mad at this kit and not ready to be "defeated" by it, so I removed the bottoms of the fin tabs from the Fin-Loks with pliers (CA is strong but I'm stronger!) and repaired the fins. They are probably not as strong as before but they're close. I tried dry fitting the fins and one was clearly never going to snap into place. After a while I realized that the fin would seat in the 'lok' when the mount was out of the body tube, but would not when the mount was in the tube. Slowly a light went on. I snapped the fins into place with the mount in my lap, and saw that one fin was tight against the centering ring. The added thickness of the tube kept the fin from seating properly. I sanded down that side of the centering ring, tested until I got all four fins dry-fit into position, and then finally glued them into place.

Here's what I suggest you do. Once the glue has set on the Fin-Lok rings and centering ring. Give the fins another dry fit test. I think I also had a very small amount of CA get into one Fin-Lok, and its important to catch that problem before you are gluing the fins. Then slide the mount into the body tube and dry fit again! Once all the fins fit nicely in the tube you are home free. I would pull the fins out one-at-a-time to glue them. Leave the others in place to support and stabilize the mount. This sounds like a lot, but if your parts fit right it will add very little time, just a minute or two. If you have a problem, this will save you a lot of anguish. Any problems you discover at this point can be easily fixed, but if you blast ahead like me you court disaster (or at least a lot of extra effort.and expletives!)

Once the fins are on you reach in through the open back of the rocket to glue the motor mount in place and apply internal fillets to the fins. (I have to admit that I resorted to epoxy with micro-balloons at this point). Then you join the body tubes with a very ample tube coupler. This is another place where CA can trip you up. The coupler tube is very tight in the body tubes, and the glue can set and grab before you get the tubes fully in place. It happened to me when I brought the top tube down onto the lower tube and coupler. I have over 200 pounds on me to contribute to the effort and I was putting all the weight I could on that tube to slide it down, but it still grabbed about ¼ inch short of the bottom tube. I eventually filled the gap with a combination of wood filler painted with CA and a bit of epoxy putty. It looks fine, but you don't want to go through that. The instructions suggest a bead of CA about an inch inside the upper body tube. I would place the glue farther in or, even better, use wood glue for these joints. It will be stronger and easier to work with (but it can still 'grab' early if you move too slowly, especially on tight fits like this!)

The "fin strakes" that give this rocket its "ARM" look must be shaped a bit. The instructions give you the dimensions very clearly. This is more the sort of thing I am used to and it went well for me (finally!). I would suggest that you measure and mark each strake carefully, then cut with a carpenter's knife. I needed several passes to make each cut. The strakes can be sanded somewhat to smooth the edges but they are not easy to shape that way, you really need the knife (or perhaps a Dremel). I held off gluing the completed strakes on the body until I had finished filling and sanding the body tube, and I suggest you do too. It makes the sanding a lot easier.

The strakes mount on the tube with CA and the launch lugs drop into pre-cut holes. So far everything has stayed on the rocket.

Finally I turned my attention to the nose cone. I'll spare you all the details, and just mention that I spent three evenings working with a power orbital sander held between my knees (wow, that tingles!) using 100 grit paper to smooth the surface of this cone. Out of the box it looked like the surface of a basketball, or a cantaloupe melon. The tip was a mass of swirling grooves and the seam was quite deep. I should have sent it back to Aerotech, but my stubbornness was up and I attacked it with a fierce determination. I emerged covered in white plastic dust holding a great looking nose cone. This one ranks up there with the nose cone of the Quest Nike Smoke as "most painful". In both cases, however, I managed to achieve a good result. Persistence pays! I touched up the surface with progressively finer grades of paper and declared the construction phase over!

Finishing:
The finishing process was pretty painless. I used several coats of gray primer, with light sanding, followed by a couple of coats of glossy white. I had filled the spirals with Elmers wood filler and the final surface looked pretty good. Aerotech suggests a gray nosecone, but I had another idea. Many photos of the real missile show a coppery looking nose, which looks good to me. I got a can of Testors copper for the nose and am very happy with the result. If you use these metallic paints just remember to apply light coats (even more important than with other paints) and don't judge the looks until it all dries, it can look uneven when wet. You should also use clear coat to protect it, as the metallic finish can scuff easily.

The kit comes with plenty of stick-on decals. It will take a while to get them all positioned, but the instructions give you good guidance. The clear coat helps protect them as well. It's a good looking rocket; dress it up right.

Construction Rating: 4 out of 5

Flight:
I have only flown it on F20-4 Econojet motors so far, but this is a great motor for this bird. Boost has been straight (despite wind) and higher than I expected, around 750 feet or more. This is just right for our field. I would like to try it on the G Econojets but I can't find any in the current shortage. The four second delay seems about right; I certainly wouldn't try it with a seven second delay.

That beefy motor clip takes some effort to pull back. I use a pair of pliers to hold the clip while I insert and remove the motor. It's nice to know that that motor is well restrained.

Recovery:
Aerotech provides a very nice 30 inch chute which brings the Strong ARM down gently. I have had some drift with mine (windy conditions) and will either reduce the chute when I fly with a G, or wait for calm winds. There is no need for wadding due to the baffle, which has worked fine for me (you never notice a baffle unit until it fails). I have no complaints about the recovery system.

Flight Rating: 4 out of 5

Summary:
I bought the Strong Arm hoping for a fast, easy build; kind of a 'vacation' from the more challenging projects. I got the good looking and good flying rocket I expected, but the build process had its frustrations, as I have described. In the grand scale of things this wasn't really so bad. I've had scratch projects get much hairier, but I expected different from an expensive kit like this. The nosecone was just a crummy part. My other problems resulted from my unfamiliarity with the Aerotech system and with CA as the primary adhesive. Many people I trust have built multiple Aerotech kits without any trouble at all, and when I build another I'm sure I won't have any either. I'll test fit the fins at each step and be careful with the CA.

Now that I'm smarter about Fin-Loks I like the idea, and the baffle is good one. Any of the Aerotech kits are good choices for a first "high-power rocket" (really "upper mid-power"). I like the look and size of the Strong Arm best. If you are careful and mindful of the warnings in the instructions you'll do fine. (.and go with copper for the nose cone! Gray is much too boring for a cool rocket like this!)

Overall Rating: 4 out of 5

The following excerpt is from "Sport Rocketry". The intention is to allow guests to get a basic feeling about a kit. We strongly suggest that you get a copy of the referenced Sport Rocketry and read the entire article. Inside you will find many helpful hints in construction as well as other useful information. For more information, use the two links above.

"Over the past few years I have found Aerotech rocket kits fun to build and fly." 
"Looking over the parts, I found everything in good shape except for one of the fin lock rings. With a phone call to Aerotech they sent me a replacement." 
"After attaching the shock cord and 30" fabric parachute to the nose cone, I worked on the long process of applying the decals. . . It took a couple of hours . . ." 
". . . E18-4W. The Strong Arm roared off the pad with its breathtaking white flame and smoke billowing out of the motor." 
"It's molded plastic fins and strakes make assembly easy and help give the rocket a great finish." 

The entire article gives the impression is that this is an good value, combining price, looks and performance, for an intermediate modeler.